2.1 : Simulations

This site makes the results of a suite of simulations available to the public.
The first of these is the Millennium Simulation, performed by Volker Springel (MPA)
using a specially customized version of the GADGET-2 simulation code. See
Springel etal (2005).
The second is the Millennium-II Simulation, perfomed by Mike Boylan-Kolchin (MPA)
using Volker Springel's GADGET-3 code. See
Boylan-Kolchin etal (2009).
Both are pure dark matter simulations in a periodic cube using 10,077,696,000 simulation particles.
The main differences between the two are the size of the box (500 Mpc/h for Millennium,
100 Mpc/h for Millennium-II), the force resolution (Plummer-equivalent softening of 5 kpc/h for Millennium,
1 kpc/h for Millennium-II), and the particle mass (8.6 x 108 Msun/h for Millennium,
6.9 x 106 Msun/h for Millennium-II).

A smaller version of the Millennium Run, the milli-Millennium Simulation, is also available on this site.
This simulation used the same cosmology and resolution as the Millennium Simulation but in a 62.5 Mpc/h box with
19,683,000 particles. A smaller version of the Millennium-II, the mini-Millennium-II was run as well.
It had the box size of the Millennium-II, the mass resolution of the Millennium and used the same initial condiftions Forier modes as
Millennium-II.

Peter Thomas has run a WMAP7 version of the Millennium run, which will be referred to as MR7 in much of this web site.
Details of this simulation are described in
Guo etal (2013)
where is is refered to by the name MS-W7.
The linear phases used for the MR7 initial conditions are taken from Panphasia -
the public multi-scale Gaussian white noise field described in
Jenkins 2013.
The phases for the MR7 simulation are published in table 6 of
Jenkins 2013, where the name MW7 is used.

The parameters for the various simulations are listed in the first table below.
Note that we add a "Code" name for each simulation that is used for table names in various places.
For example halo merger trees derived form the simulations and stored in the database
MPAHalotrees uses these shorthand names.
Similarly for galaxy catalogues derived from these in
Guo2013a.

Code

Name

Ωm = Ωdm+Ωb

Ωb

ΩΛ

h = H0/100 km/s/Mpc

ns

σ8

Np

mp (Msun/h)

L (Mpc/h)

ε (kpc/h)Plummer-equivalent force softening

MR

Millennium

0.25

0.045

0.75

0.73

1

0.9

21603

8.61 x 108

500

5

mMR

milli-Millennium (millimil)

0.25

0.045

0.75

0.73

1

0.9

2703

8.61 x 108

62.5

5

MRII

Millennium-II

0.25

0.045

0.75

0.73

1

0.9

21603

6.88 x 106

100

1

mMRII

mini-Millennium-II (miniMilII)

0.25

0.045

0.75

0.73

1

0.9

4323

8.61 x 108

100

5

MR7

Millennium-WMAP7

0.272

0.0455

0.728

0.704

0.967

0.81

21603

9.31 x 108

500

5

The second table contains entries that do not represent real simulations, but are scaled versions of
a real simulation indicated by its code in the "Original simulation" column.
Using the scaling algorithm from
Angulo & White (2010)
one can approximate catalogues as they would have
been obtained had the simulation been run with a different cosmology.